In existing aircraft, the engines such as bypass and twin-spool turbojet engines are suspended underneath the wing structure or attached to the fuselage by complex attachment devices also referred to as EMSs (which stands for “engine mounting structure”), or else attachment pylons. The attachment pylons usually employed have a primary structure, also referred to as a rigid structure. This primary structure generally forms a box section, which means to say that it is made by assembling lower and upper longitudinal members joined together by a plurality of transverse stiffening ribs situated inside the box section. The longitudinal members are arranged on the lower and upper faces, while lateral panels close the box section on the lateral faces.
The primary structure of these attachment devices is designed to allow the static and dynamic loads generated by the engines, such as the weight, thrust or else various dynamic loads to be transmitted to the wing structure.
In solutions known from the prior art, the transmission of force between the engine and the primary structure is performed by attachments made up of a forward engine mount, a rear engine mount and a thrust force reacting device. These elements together form a statically determinate attachment system.
Usually, the forward engine mount is fixed to the outer ring section of an intermediate case or to the fan case, as disclosed in document FR 3 014 841. Alternatively, this forward engine mount may be attached to the hub of the intermediate case, connected by radial arms to the aforementioned outer ring section. The rear engine mount itself connects the primary structure to the exhaust case of the engine, situated at the rear end of this engine.
The attachment thus ensures that force is transmitted to the pylon, while at the same time limiting the internal deformation of the engine. However, ultra-high bypass ratio engines have a fan of increasingly high diameter, with a view to improving their performance in terms of fuel consumption. However, this sizing generally causes an increase in the flexibility of the engine, the consequence of this being a drop in performance associated with the turbine blade tip clearances. Specifically, the flexural deformation of the engine leads to wearing of the blades of the high-pressure and low-pressure turbines and compressors, which creates significant clearances at the blade tips and reduces the performance/efficiency of the engine (or increases its fuel consumption).
There is therefore still a need to limit the deformation of the engine.